Synthesis and fluorescence behavior of 3-methacryamide-9-carbazole and itspolymer

A novel acrylic monomer-bearing carbazole chromophore, 3-methacrylamide-9-e thyl-carbazole and its model compound 3-isobutyramide-9-ethylcarbazole were synthesized by reaction of 3-amino-9-ethyl carbazole and the corresponding acyl chloride in the presence of triethylamine. It can be polymerized easi ly by using azobisisobutyronitrile as an initiator or photopolymerized with out any sensitizer. The photochemical behavior of 3-methacrylamide-9-ethyl- carbazole, ifs polymer and 3-isobutyramide 9-ethylcarbazole were investigat ed by recording the fluorescence spectra in N,N-dimethylformamine. It was f ound that the fluorescence intensify of the monomer is dramatically lower t han those of its polymer and the model compound in the same chromophore con centration. This phenomenon, termed as the 'structural self-quenching effec t: was commonly observed for acrylic monomers bearing chromophore moieties and ascribed to the coexistence of the electron-donating chromophore and th e electron-accepting double bond within one molecule. The strong fluorescence of the polymer can be quenched by adding electron-d eficient monomers having no chromophore moieties such as methyl methacrylat e and acrylonitrile, and the Stern-Volmer constants were determined. It is observed that the higher the electron deficiencies of the quenchers, the hi gher the Stern-Volmer constants, implying a stronger quenching effect. Copy right (C) 2000 John Wiley & Sons, Ltd.